Pharmaceutical compositions are used in various forms. For example, when used in the forms of suspensions and cake compositions, pharmaceutical compositions contain, in addition to a medicament contained as an active ingredient, additives, such as a defoaming agent, an excipient, a suspending agent, a buffer, a bulking agent, a lubricant, a fluidizer, a disintegrant, a binder, a surfactant, a preservative, a flavoring agent, an odor improving agent, and a tonicity agent. The defoaming agent is added to suppress liquid foaming, and is commonly used for preparing pharmaceutical compositions of forms including suspensions and cake compositions (see, for example, JP-A-2002-114674, WO/2005/032569, and JP-A-2010-13364).
Silicone oil used as pharmaceutical compositions is used as bases and defoaming agents, and because of their foam-suppressing small surface tension and very low toxicity, silicone oil represents a particularly useful additive for pharmaceutical compositions (see, for example, Iyakuhin Tenkabutsu Jiten 2007, International Pharmaceutical Excipients Council Japan, Jul. 25, 2007, p. 143, and JP-A-6-116170 and JP-A-2003-81882).
Aripiprazole, which is used as an active ingredient in pharmaceutical compositions, has the following structural formula (I):

Aripiprazole is known as an atypical antipsychotic useful for the treatment of schizophrenia (U.S. Pat. No. 5,006,528).
Furthermore, a compound (7-[4-(4-benzo[b]thiophen-4-yl-piperazin-1-yl)butoxy]-1H-quinolin-2-one) represented by structural formula (II):
which is used as an active ingredient in pharmaceutical compositions is also known as an atypical antipsychotic useful for the treatment of schizophrenia (JP-A-2006-316052).